//
//  ViewController.swift
//  ViewAnimation
//
//  Created by 涂晶 on 16/6/8.
//  Copyright © 2016年 TuJing. All rights reserved.
//

import UIKit
import QuartzCore

class SnowView: UIView {
  
  override init(frame: CGRect) {
    super.init(frame: frame)
    
    let emitter = layer as! CAEmitterLayer
    emitter.emitterPosition = CGPoint(x: bounds.size.width / 2, y: 0)
    emitter.emitterSize = bounds.size
    emitter.emitterShape = kCAEmitterLayerRectangle
    
    let emitterCell = CAEmitterCell()
    emitterCell.contents = UIImage(named: "flake.png")!.CGImage
    emitterCell.birthRate = 200
    emitterCell.lifetime = 3.5
    emitterCell.color = UIColor.whiteColor().CGColor
    emitterCell.redRange = 0.0
    emitterCell.blueRange = 0.1
    emitterCell.greenRange = 0.0
    emitterCell.velocity = 10
    emitterCell.velocityRange = 350
    emitterCell.emissionRange = CGFloat(M_PI_2)
    emitterCell.emissionLongitude = CGFloat(-M_PI)
    emitterCell.yAcceleration = 70
    emitterCell.xAcceleration = 0
    emitterCell.scale = 0.33
    emitterCell.scaleRange = 1.25
    emitterCell.scaleSpeed = -0.25
    emitterCell.alphaRange = 0.5
    emitterCell.alphaSpeed = -0.15
    
    emitter.emitterCells = [emitterCell]
  }
  
  required init(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
  
  override class func layerClass() -> AnyClass {
    return CAEmitterLayer.self
  }
  
}
